A transient ischemic attack, or mini-stroke, occurs when blood flow to part of the brain becomes temporarily blocked, which causes stroke-like symptoms.
Even though symptoms typically clear up fairly quickly, a mini-stroke is still a medical emergency as it can precede having a stroke.
The authors of a new study published in Neurology, the medical journal of the American Academy of Neurology, note that most research on post-mini-stroke care mainly focuses on stroke prevention, so they wanted to take a closer look at dementia after a transient ischemic attack.
Their observational study found an association between mini-strokes and a higher long-term risk of dementia.
According to the American Stroke Association, around 240,000 people in the United States have a mini-stroke each year. Nearly one in five people with a suspected transient ischemic attack have a stroke within 90 days.
The symptoms of a transient ischemic attack are similar to those of a stroke and can include:
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To learn more about dementia risk following a transient ischemic attack, the research team analyzed 20 years of healthcare data. The study included more than 110,000 people who had their first mini-stroke.
The participants had an average age of 70, and about half were women. The team did not include anyone who had a history of a prior stroke or dementia.
The researchers matched each participant from the transient ischemic attack group with a person from the general population who had not experienced a mini-stroke or stroke.
The team also compared around 100,000 people who had had a transient ischemic attack with matched participants who had experienced a first stroke. This helped the researchers to examine how dementia risk compared between the two groups.
During follow-up, 19.3% of participants who had had a transient ischemic attack received a diagnosis of dementia, compared with 15.2% of matched participants without a mini-stroke or stroke history.
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After accounting for health and demographic factors, the researchers associated transient ischemic attacks with a 34% higher overall dementia risk. The risk was 75% higher during the first year and was elevated throughout 20 years of follow-up.
Study author Raed Joundi, MD, DPhil, told Medical News Today that the early increase may partly be due to people having follow-up medical care.
“What is particularly interesting is that the increased risk did not disappear after that early period but remained elevated over the long term,” Joundi said.
Compared with participants who experienced a stroke, those who had had a transient ischemic attack had a 33% lower dementia risk during the first year.
However, this difference narrowed, and the two groups developed new dementia diagnoses at similar rates after about 5 years.
Among participants with a history of mini-stroke, dementia also occurred about three times as often as a subsequent stroke. Accounting for strokes that occurred during follow-up only modestly weakened the association between mini-strokes and dementia.
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One limitation was that the study did not include detailed brain imaging or cognitive testing, so researchers could not identify the type of dementia that the participants developed.
Joundi emphasized that increased risk does not mean dementia is inevitable.
“Someone who has a [transient ischemic attack] is not destined to develop dementia; most people in our study did not develop dementia,” he said.
Even though the study does not establish that transient ischemic attacks cause dementia, the association may be clinically significant enough to warrant closer attention to cognitive health during post-mini-stroke care.
Christopher Yi, MD, a board-certified vascular surgeon at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, who was not involved in the study, told MNT that the findings broaden how clinicians should view transient ischemic attacks.
“This study suggests that we also need to think about the long-term risk of cognitive decline and dementia,” said Yi.
Since the study was observational, Yi cautioned that it could not establish that a transient ischemic attack directly causes dementia.
Instead, he said that mini-strokes may indicate underlying vascular or brain disease that contributes to both conditions.
Yi noted that while the findings do not establish a need for formal cognitive testing, clinicians could consider establishing a cognitive baseline and asking patients and families about changes.
“A [transient ischemic attack] should never be dismissed simply because the symptoms went away,” he emphasized.
